Appendix C:

Air Quality

Discipline Report

Point Defiance Bypass 

Project

Air Quality

Discipline Report

September 2012

Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page i

Table of Contents

Summary......................................................................................................................................................... 1

Chapter 1 – Project Description ...................................................................................................................... 3

Introduction................................................................................................................................................. 3

Purpose and Need ..................................................................................................................................... 3

What alternatives are being considered for the Point Defiance Bypass Project? ....................................... 4

What’s happening in the bypass corridor today?........................................................................................ 5

What would happen if the Project were not built?....................................................................................... 5

What are the proposed improvements and related activities of the Point Defiance Bypass Project?......... 5

What are the proposed operational changes that would result from the Point Defiance Bypass Project?.. 6

Chapter 2 – Methodology................................................................................................................................ 8

Why should air quality be reviewed? .......................................................................................................... 8

What policies or regulations are related to effects on air quality?............................................................... 8

What are the requirements for evaluating air quality? ................................................................................ 9

What standards apply to air quality? ........................................................................................................ 12

How is the analysis methodology applied?............................................................................................... 13

How were Project operational emissions analyzed? ................................................................................ 14

What Project intersections were analyzed?.............................................................................................. 14

How were signalized intersections analyzed using the WASIST model? ................................................. 16

Chapter 3 – Affected Environment ................................................................................................................ 17

What are the Puget Sound regional air quality trends? ............................................................................ 17

What are the current air quality characteristics in the study area? ........................................................... 18

What pollutants of concern exist in the study area? ................................................................................. 20

What are the health effects from MSATs?................................................................................................ 24

How do climate and weather affect air quality? ........................................................................................ 25

What are the existing meteorology conditions?........................................................................................ 25

Chapter 4 – Project Effects ........................................................................................................................... 27

What air pollutants would the Project generate? ...................................................................................... 27

What are the construction effects caused by the Project?........................................................................ 27

What are the operational effects caused by the Project? ......................................................................... 28

What are the indirect and cumulative effects of the Project?.................................................................... 32

Chapter 5 – Recommended Minimization Measures..................................................................................... 34

What minimization measure will be taken during Project construction? ................................................... 34

What minimization measures will be taken during Project operation?...................................................... 36

References.................................................................................................................................................... 37
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Table of Exhibits

Exhibit 1. Build Alternative Components ......................................................................................................... 7

Exhibit 3. National, State, and Local Ambient Air Quality Standards............................................................. 12

Exhibit 2. Level of Service and Delay for the At-Grade Intersections (PM Peak Hour) ................................. 15

Exhibit 2. Ambient Criteria Pollutant Concentrations at Monitors Closest to the Study Area......................... 19

Exhibit 4. Estimated Operational Emissions.................................................................................................. 29

Exhibit 5. Maximum Predicted CO Concentrations ....................................................................................... 31
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 1

Summary

What is the existing air quality in the study area?

The Project is in a maintenance area for carbon monoxide (CO) 

and coarse particulate matter (PM10), and a nonattainment area for 

fine particulate matter (PM2.5). Although this area is also 

designated as a maintenance area of 1-hour ozone (O3), due to US 

Environmental Protection Agency’s (USEPA) recent updates to the 

Clean Air Act (CAA), conformity regulations no longer apply.

What are the project effects on air quality in the study 

area?

The Project is not subject to the Transportation Conformity rules 

because it is not an FHWA or Federal Transit Administration 

(FTA) project; however, because it is located in areas designated 

as maintenance or nonattainment for NAAQS pollutants, it is 

subject to the General Conformity rules (40 CFR 93, Subpart B). 

The emissions estimates presented in this report indicate that the 

Project’s emissions, due to construction and operation, would be 

below the de minimis levels listed in the General Conformity rules, 

and so implementation of the Project would be in conformance 

with CAA requirements.

In addition, CO concentrations were calculated at busy 

intersections (grade crossings) expected to have peak hour delays. 

CO concentrations were estimated for the existing (2010) and 

future (2030) years using the WSDOT Washington State 

Intersection Screening Tool (WASIST). The results were 

compared to the National Ambient Air Quality Standards 

(NAAQS) for CO. The Project CO hot spot analysis performed for 

congested intersections show that both 1-hour and 8-hour averaged 

CO concentrations would be below the NAAQS in the existing 

year (2010), the year of opening (2017), and the horizon year 

(2030) for the constructed Project at all modeled intersections.
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Based on the results of the traffic analysis, the Project is not predicted 

to affect regional vehicle miles traveled. MSAT levels in the study 

area are predicted to decrease significantly in the future due to 

federally mandated programs. The Project is not expected to impact 

this reduction.
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Air Quality Discipline Report Page 3

Chapter 1 – Project Description

Introduction

Under the High-Speed Intercity Passenger Rail (HSIPR) Program and 

pursuant to a programmatic Tier I Environmental Assessment (EA) the 

Federal Railroad Administration (FRA) has approved an application from 

the Washington State Department of Transportation (WSDOT) to improve 

the Pacific Northwest Rail Corridor (PNWRC), a federally designated 

high-speed rail corridor. One project included in the PNWRC application 

is the Point Defiance Bypass Project (the Project), which would respond to 

deficiencies in the existing rail operations around Point Defiance. This 

Discipline Report has been prepared in support of the project-specific EA 

for the Point Defiance Bypass project.

The Project is located in Pierce County along an existing approximately 

20-mile rail corridor between Tacoma and Nisqually.

1 The Project would 

provide for the re-routing of Amtrak passenger trains from the BNSF rail 

line that runs along the southern Puget Sound shoreline (Puget Sound 

route) to the Point Defiance Bypass route, an existing rail corridor that 

runs along the west side of I-5. The Project would consist of railroad track 

and support facility improvements, and relocation of the Tacoma Amtrak 

Station to Freighthouse Square in Tacoma.

Purpose and Need

As described above, the Point Defiance Bypass route is part of the larger 

PNWRC. Within Washington State, the vision for the PNWRC is to 

“...improve intercity passenger rail service by reducing travel times and 

achieving greater schedule reliability in order to accommodate growing 

intercity travel demand...”2

.

The purpose of the Project is to provide more frequent and reliable highspeed intercity passenger rail service along the PNWRC between Tacoma 

and Nisqually. In conformity with the decisions under the Tier 1 

Programmatic EA, the PNWRC Improvement Program has reduced the 

overall environmental effects of providing improved passenger rail service 

 1 The three owners of the project corridor are Sound Transit, Tacoma Rail, and BNSF. 2 WSDOT 2009
September 2012 Point Defiance Bypass Project

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with the use of an existing transportation corridor and associated 

infrastructure, rather than creating a new corridor.

The Project is needed to address the deficiencies in the existing rail 

alignment around Point Defiance. The existing alignment (Puget Sound 

route), shared by freight and passenger rail traffic, is near capacity and is 

therefore unable to accommodate additional high-speed intercity 

passenger rail service without substantial improvements. In addition, the 

existing alignment has physical and operational constraints that adversely 

affect both passenger train scheduling and reliability.

Improving intercity passenger rail service in the project area and meeting 

the Project needs would be accomplished by:

• Enhanced Frequency: Increasing Amtrak Cascades round-trips from four 

to six by 2017 to meet projected service demands.

• Improved Reliability: Reducing scheduling conflicts with freight trains 

that often result in delays, and by minimizing or avoiding operational 

delays (e.g., drawbridge openings) and weather-related delays (e.g., 

mudslides), and improving on-time performance from 68 percent to 88 

percent.

• Enhanced Efficiency: Enhancing the efficient movement of people by 

decreasing trip times by 10 minutes, and reducing the amount of time 

passenger trains spend yielding to freight movements.

• Improved Safety: Constructing at-grade crossings with upgraded safety 

features, including wayside horns, median barriers, advance warning 

signals, and traffic signal improvements.

What alternatives are being considered for the Point 

Defiance Bypass Project?

FRA and WSDOT conducted an evaluation of three build alternatives: the 

Point Defiance Bypass Alternative, the Shoreline Alternative, and the 

Greenfield Alternative. Two of the alternatives (the Shoreline Alternative, 

and the Greenfield Alternative) were eliminated from further study. 

Although both alternatives could meet the Project’s purpose and need, 

they were determined to be impracticable and unfeasible due to technical 

constraints, high construction costs, and significant environmental effects. 

Grade separations were also evaluated for further consideration. FRA and 

WSDOT’s preliminary analysis revealed that current and projected future 

traffic volumes do not warrant the construction of new grade-separated 

crossings. 
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 5

What’s happening in the bypass corridor today?

The rail line between TR Junction and East “D” Street in Tacoma hosts 

both freight and commuter trains, including freight operators Tacoma Rail 

and BNSF, and Sound Transit’s Sounder commuter rail service. Freight 

train traffic between TR Junction and East “D” Street averages under two 

trains per day, while Sound Transit currently operates 18 trains per day 

between Freighthouse Square and Seattle each weekday, and also offers 

occasional special event trains, usually on weekends, to serve sporting and 

other events in Seattle. Sounder service to Lakewood begins in late 2012.

What would happen if the Project were not built?

If the Project were not built (the No Build Alternative), Amtrak’s 

Cascades and Coast Starlight passenger train service would continue to 

use the existing Puget Sound route. The No Build Alternative includes 

only the minor maintenance and repair activities necessary to keep the 

existing Puget Sound route operational. With the No Build Alternative, it 

would be expected that as freight traffic increases, congestion would 

adversely affect Amtrak service reliability, and the travel time for Amtrak 

trains between Seattle and Portland would increase.

Along the Point Defiance Bypass route, the Tacoma Rail and BNSF 

freight services would continue. The at-grade crossings at Clover Creek 

Drive Southwest, North Thorne Lane Southwest, Berkeley Street 

Southwest, 41st Division Drive, and Barksdale Avenue Southwest would 

not be upgraded.

Sound Transit’s Sounder commuter passenger trains will become 

operational in late 2012 between the Tacoma Dome Station at 

Freighthouse Square in Tacoma and Sound Transit’s Lakewood Station 

(on the Point Defiance Bypass route) with as many as 18 Sounder trains 

per day.

What are the proposed improvements and related activities

of the Point Defiance Bypass Project?

The Project consists of railroad track and support facility improvements, 

and the relocation of Amtrak’s Tacoma Station. Exhibit 1 shows the 

components of the Build Alternative. The following details specific 

components of the Build Alternative.

• Construct New Track Adjacent to the Existing Main Line – A new 

3.5-mile track adjacent to the existing main line would be constructed 

from South 66th Street (Rail MP 6.9) in Tacoma to between Bridgeport 
September 2012 Point Defiance Bypass Project

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Way SW (Rail MP 10.4) and Clover Creek Drive SW (Rail MP 10.9) in 

Lakewood.

• Reconstruct and Rehabilitate the Existing Main Line – Starting just 

southwest of Bridgeport Way Southwest (Rail MP 10.4) in Lakewood, the 

existing track would be reconstructed to a location southeast of the I5/Mounts Road Southwest interchange (Rail MP 19.8) at Nisqually 

Junction.

• Improvements at at-Grade Crossings – Several grade crossings would 

be improved with wayside horns, gates, traffic signals and signage, 

sidewalks, median separators, and warning devices. These crossings 

include Clover Creek Drive Southwest, North Thorne Lane Southwest, 

Berkeley Street Southwest, 41st Division Drive and Barksdale Avenue.

• Tacoma Amtrak Station Relocation – The existing Tacoma Amtrak 

Station would be relocated from its Puyallup Avenue location to the 

Tacoma Dome Station at Freighthouse Square, at 430 E. 25th Street in 

Tacoma.

What are the proposed operational changes that would 

result from the Point Defiance Bypass Project?

Amtrak’s existing Cascades and Coast Starlight passenger train service 

would be rerouted from the Puget Sound route along the Puget Sound 

shoreline to the Point Defiance Bypass route. The Project would also 

provide for additional Amtrak Cascades service by increasing the number 

of round trips provided from 4 to 6, or a total of 12 Cascades service train 

trips. Amtrak Coast Starlight would also travel on the Point Defiance 

Bypass route for a total of two Coast Starlight service train trips. The 

speed of these passenger trains would be up to 79 mph.
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Exhibit 1. Build Alternative Components
September 2012 Point Defiance Bypass Project

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Chapter 2 – Methodology

Why should air quality be reviewed?

Air quality is typically evaluated, either qualitatively or quantitatively, as 

part of the NEPA review process for large projects that receive federal 

funding or approvals. The level and type of such analysis is selected 

proportional with the potential for adverse air quality effects due to 

construction or operation of a project. 

In addition to meeting the general NEPA review requirements, projects 

that are funded, approved, or permitted by federal agencies, may need to 

meet air quality conformity requirements. Conformity refers to the need 

for federal actions to be in conformance with the applicable State 

Implementation Plans (SIPs) to attain or maintain compliance with 

National Ambient Air Quality Standards as required under the federal 

CAA.

What policies or regulations are related to effects on 

air quality? 

Air quality resources are managed and regulated by multiple agencies. 

Governing air quality plans and policies, as well as applicable regulations 

and regulatory agencies are listed below.

The federal CAA and its amendments and the Washington State Clean Air 

Act regulate air quality in the Puget Sound region, and the USEPA, the 

Washington State Department of Ecology (Ecology), and the Puget Sound 

Clean Air Agency (PSCAA) enforce those regulations in the study area. 

The USEPA delegates authority to manage air quality issues to the states.

In Washington State, the USEPA and Ecology further delegate authority 

to local air quality agencies. PSCAA is the local air agency for the Puget 

Sound region. Projects that potentially affect air quality in nonattainment 

or maintenance areas must conform to air quality plans, policies, and time 

tables for attaining or maintaining federal health-based air quality 

standards through the air quality conformity rules. 
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Air Quality Discipline Report Page 9

What are the requirements for evaluating air quality?

Criteria (NAAQS) Pollutants

A conformity determination is required for each federal action, excluding

exempt actions, which may adversely impact a nonattainment or 

maintenance area. A nonattainment area is defined as an area that is 

currently designated as not meeting NAAQS; a maintenance area is 

defined as an area that has not met NAAQS at some time during the past 

20 years.

There are two bodies of conformity rules that can apply to federal actions:

1. Transportation Conformity rules, provided under 40 CFR 93, 

Subpart A, which apply to projects funded or approved by the 

FHWA or FTA; or where any funds are provided under Title 23 

of the United States Code (USC), or the Federal Transit Act (49 

USC 1601 et seq.); and

2. General Conformity rules (40 CFR 93, Subpart B), which apply 

to all other federal actions.

If a project is not subject to the Transportation Conformity rules, it is then 

covered under the General Conformity rules. Because the Project is not an 

FHWA/FTA project as defined in 40 CFR 93, it must be reviewed with 

respect to the General Conformity requirements. The air quality analysis 

presented in this report quantifies annual operational locomotive CO, 

PM10, and PM2.5 (including PM2.5 precursors SO2, NOx, and Volatile 

organic compound [VOC]) emissions associated with the Amtrak 

Cascades and Amtrak Coast Starlight service within the project limits and 

compares it to annual emission limits allowable under the General 

Conformity rules.

In the past, the region has exceeded O3 standards. The current status, as 

determined by the USEPA is that the Pierce County portion of the SeattleTacoma air quality management area is a maintenance area for the 

revoked 1-hour O3 standard. 

The Phase 1 final rule to implement the 8-hour O3 standard was published 

on April 30, 2004. The anti-backsliding provisions in that rule set forth 

specific requirements for areas that are designated attainment for the 8-

hour O3 standard; and that were - at the time of the 8-hour designations 

(generally June 15, 2004) - either attainment areas with maintenance plans 

for the 1-hour standard; or nonattainment for the 1-hour standard.

Specifically, 40 CFR part 51, section 51.905(a)(3) and (4) requires these 

areas to submit a maintenance plan under section 110(a)(1) of the CAA. 

That maintenance plan must demonstrate maintenance out to 10 years after 
September 2012 Point Defiance Bypass Project

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designation. This maintenance plan does not, however, carry with it any 

conformity obligations, unlike maintenance plans required under section

175A of the CAA.

Therefore, the Pierce County portion of the historic 1-hour O3

maintenance area maintains a 1-hour ozone maintenance plan, but does 

not require O3 standard conformity analyses for projects located within 

this region. Therefore, estimates of O3 or O3 precursors were not included 

in the General Conformity analysis included in the report.

While the Project is not covered under Transportation Conformity 

requirements, the Project is expected to impact traffic conditions at a 

number of highway/rail (at-grade) crossings. Therefore, some air quality 

analysis procedures typically used for projects covered by Transportation 

Conformity rules were used to assess potential air quality effects of the 

Project for NEPA review purposes.

One of these procedures, a CO hot-spot analysis, was performed. CO hotspots were modeled using the WSDOT WASIST model (version 2.0). 

WASIST is a Windows-based screening model used for determining 

worst-case CO concentrations at signalized intersections throughout the 

State of Washington. WASIST uses readily available data in a userfriendly application to make a conservative estimate of project-related CO 

levels. This is done by using a combination of worst-case conditions that, 

when occurring simultaneously, produce the highest levels of CO. If the 

results from WASIST do not violate NAAQS for CO, the impact from any 

other combination of conditions would also be below the standards and no 

further modeling is required.

In some cases, projects subject to the Transportation Conformity 

requirements in PM2.5 nonattainment and maintenance areas also perform 

a PM hot spot analysis for projects of local air quality concern (as 

described in 40 CFR 93.123). 

Section 93.123(b)(1) of the Transportation Conformity rule defines the 

projects that require a PM2.5 or PM10 hot-spot analysis as:

1. New highway projects that have a significant number of diesel 

vehicles, and expanded highway projects that have a significant 

increase in the number of diesel vehicles;

2. Projects affecting intersections that are at LOS D, E, or F with a

significant number of diesel vehicles, or those that would

change to LOS D, E, or F because of increased traffic volumes 

from a significant number of diesel vehicles related to the 

project;
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 11

3. New bus and rail terminals and transfer points that have a 

significant number of diesel vehicles congregating at a single 

location;

4. Expanded bus and rail terminals and transfer points that 

significantly increase the number of diesel vehicles 

congregating at a single location; and

5. Projects in or affecting locations, areas, or categories of sites 

which are identified in the PM2.5 or PM10 applicable 

implementation plan or implementation plan submission, as 

appropriate, as sites of violation or possible violation.

The Project does not include significant numbers of diesel vehicles, would 

not significantly change the roadway network, and would not include 

terminals or transfer points where vehicles would congregate. Therefore, a 

PM hot spot analysis was not performed.

Mobile Source Air Toxics (MSATs) 

In addition to the criteria pollutants for which there are NAAQS, the 

USEPA also regulates air toxics. Toxic air pollutants are those pollutants 

known or suspected to cause cancer or other serious health effects. 

The CAA identified 188 air toxics, and 21 have been identified with 

mobile sources. In 2001, the USEPA identified six of the 21 mobile 

sources as priority MSATs. The six priority MSATs include:

• Benzene

• Formaldehyde

• Diesel particulate matter/diesel exhaust organic gases

• Naphthalene

• Acrolein

• 1,3-Butadiene

In 2009, the FHWA issued interim guidance on MSATs is considered the 

best practice for determining the appropriate level of MSAT analysis for 

transportation projects. FHWA has suggested the following three-tiered 

approach for determining potential project-induced MSAT effects:

• Tier 1 – No analysis for projects that have no potential for 

meaningful MSAT effects;

• Tier 2 – Qualitative analysis for projects with a low potential 

MSAT effects; and

• Tier 3 – Quantitative analysis to differentiate alternatives for 

projects that have higher potential MSAT effects. 

MSAT emissions are discussed qualitatively for the Project because the

types of projects included in this category improve operations of highway, 
September 2012 Point Defiance Bypass Project

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transit, or freight without adding substantial new capacity or creating a 

facility that is likely to meaningfully increase MSAT emissions.

What standards apply to air quality? 

Washington State is subject to air quality regulations issued by the 

USEPA, Ecology, and local air agencies. USEPA’s NAAQS set limits on 

concentration levels of criteria pollutants. Concentration levels of the 

criteria pollutants must not exceed the NAAQS over specified time 

periods. Ecology and PSCAA monitor air quality in the Puget Sound 

region to compare the levels of criteria pollutants found in the atmosphere 

with the NAAQS. 

The NAAQS consist of two sets of standards: the primary standards, and 

the secondary standards. The “primary” standards have been established to 

protect the public health. The “secondary” standards are intended to 

protect the nation’s welfare, and they account for air pollutant effects on 

soil, water, visibility, materials, vegetation, and other aspects of the 

general welfare. In addition to these standards, Ecology and PSCAA have 

adopted state and local ambient air quality standards that are equivalent to, 

or more stringent than, the USEPA’s NAAQS. Exhibit 2 summarizes the 

ambient air quality standards applicable in the study area.

Exhibit 2. National, State, and Local Ambient Air Quality Standards

Pollutant

National Standards

Washington 

State

Puget Sound 

Primary Secondary Region

Nitrogen Dioxide (NO2)

Annual Average (ppm) a 0.053 0.053 0.05 0.05

1-hour Average (ppm) 0.1 NS NS NS

Carbon Monoxide (CO)

8-hour Average (ppm)b 9 NS 9 9

1-hour Average (ppm) b 35 NS 35 35

Ozone (O3)

8-hour Average (ppm) c 0.075 0.075 0.08 NS

1-hour Average (ppm) NS NS 0.12 0.12

Lead (Pb)

Maximum Arithmetic Mean (μg/m3 averaged 

over calendar quarter) 1.5 1.5 NS 1.5

Sulfur Dioxide (SO2)

Annual Arithmetic Average (ppm) NS NS 0.02 0.02

24-hour Average (ppm) NS NS 0.10 0.10

3-hour Average (ppm) d NS 0.50 NS NS

1-hour Average (ppm) e 0.075 NS 0.40 0.40

Particulate Matter 
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Exhibit 2. National, State, and Local Ambient Air Quality Standards

Pollutant

National Standards

Washington 

State

Puget Sound 

Primary Secondary Region

PM10

Annual Arithmetic Average (μg/m3) NS NS 50 50

24-hour Average (μg/m3) 150 150 150 150

PM2.5

Annual Arithmetic Average (μg/m3) f 15 15 NS NS

24-hour Average (μg/m3) g 35 35 NS NS

Total Suspended Particulates (TSP)

Annual Arithmetic Average (μg/m3) NS NS 60 NS

24-hour Average (μg/m3) NS NS 150 NS

ppm = parts per million

μg/m3 = micrograms per cubic meter

PM10 = particulate matter smaller than 10 microns in diameter

PM2.5 = particulate matter smaller than 2.5 microns in diameter

NS = no standard

Notes:

a To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at 

each monitor within an area must not exceed 0.100 ppm (effective January 22, 2010).

b Not to be exceeded more than once per year.

c To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone 

concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm (effective 

May 27, 2008).

d Note that the federal 3-hour SO2 standard is a secondary standard set to protect public welfare, rather 

than a primary standard set to protect public health.

e To attain this standard, the 3-year average of the 99th percentile of the annual distribution of the daily 

maximum 1—hour average concentration must not exceed 75 ppb.

f To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single 

or multiple community-oriented monitors must not exceed 15.0 μg/m3.

g To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each 

population-oriented monitor within an area must not exceed 35 μg/m3.

How is the analysis methodology applied?

As described earlier, the Project would be subject to the General 

Conformity rules to demonstrate that the proposed action is in 

conformance with the SIP. This type of conformity determination is 

required only for those pollutants for which the area is classified as 

nonattainment or maintenance, or for pollutants which are precursors to 

the nonattainment or maintenance pollutants.

The study areas for air quality are based on the NAAQS pollutants of 

concern for transportation-related projects, and vary in their extents based 

upon the characteristics of specific pollutants of concern and their 

resulting area of influence. 
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For on-road vehicle-related CO, the areas of concern are highly localized 

and typically occur close to congested roadway intersections. Therefore, 

the study area for the CO hot spot analysis related to congested roadway 

intersections is a series of intersections which have traffic flows that are 

affected by the Project and that are within a narrow corridor along either 

side of the railroad tracks. 

For the General Conformity analysis, emissions of nonattainment and 

maintenance area pollutants (CO, PM10 and PM2.5 [(including PM2.5 

precursors SO2, NOx, and VOCs]) from construction and locomotive 

operations on the project rail alignment were considered on a wider 

geographic scale. Therefore, the study area for these pollutants consists of 

the entire Seattle/Tacoma metropolitan area. 

Estimated construction and operational emissions under the General 

Conformity analysis would not be subject to the requirements of 40 CFR 

93, Subpart B, if the total emissions of each pollutants are below the 

General Conformity applicability threshold of 100 tons per year.

How were Project operational emissions analyzed?

Operational emissions from Amtrak locomotives were calculated as part 

of the General Conformity analysis to determine annual emissions of CO, 

PM10, and PM2.5 (including PM2.5 precursors).

Emissions were calculated using operational data for Amtrak service 

under the Build Alternative and USEPA emission factors for locomotives 

(USEPA, 1997). Annual operational emissions estimates were 

conservatively derived assuming Tier 0 locomotives (manufacture years 

1973 to 2001) emission factors for the Amtrak trains. Remanufactured 

Tier 0 (Tier 0+) or later locomotives (Tier 1 through Tier 4) would have 

emissions lower then the estimate made for this discipline report.

What Project intersections were analyzed?

Although many pollutants are present in vehicle exhaust, CO is the major 

pollutant of concern for transportation projects. Because the study area is 

in a maintenance area for CO, a project-level analysis is necessary to 

verify that no localized effects would cause or contribute to a violation of 

the NAAQS. The analysis of operational effects involves estimating the 

CO emissions generated by vehicles in the project vicinity and using the 

WASIST screening tool to estimate the ambient concentration at receptors 

placed around the intersections analyzed. 

Intersection screening begins with a ranking of project-affected, signalized 

intersections by level of service (LOS), and average delay. LOS is a 

measure of the weighted average vehicle delay during the peak traffic 
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 15

period at a signalized intersection on a scale of A to F, with A being the 

least congested with a short delay, and F representing the worst congested 

with a longer delay. 

Because the LOS in the study area during the PM peak hour is generally 

worse than during the AM peak hour LOS, the PM peak hour traffic data 

and LOS in the existing year, opening year, and design year were used to 

rank intersections for the Project. At grade crossing intersections within 

the study area are listed in Exhibit 2.

Exhibit 3. Level of Service and Delay for the At-Grade Intersections (PM Peak Hour)

2010

Existing Year

LOS/Delay

2030

LOS/Delay

No-Build Build

Intersection Name LOS

Average 

Delay LOS

Average 

Delay LOS

Average 

Delay

E. “D” Street and E. 26th Street B 10.7 E 72.5 E 72.6

E. “D” Street and E. 25th Street B 12.8 C 21.6 C 21.9

E. “C” Street and E. 25th Street A 10.0 B 17.3 B 17.4

S. Wilkeson Street and S. Tacoma Way B 13.3 B 19.3 B 19.4

S. Wilkeson Street and S. Center Street C 24.1 D 38.1 D 38.2

S. Pine Street and S. Tacoma Way C 26.8 D 38.0 D 38.9

S. Pine Street and S. Center Street C 32.3 D 35.3 D 36.6

35th Street SW and S. Tacoma Way B 17.1 B 18.2 B 18.2

S. 56th Street and S. Tacoma Way C 24.4 C 27.2 C 27.9

S. 74th Street and S. Tacoma Way D 36.9 D 36.1 D 37.2

Steilacoom Blvd SW and Lakeview Avenue SW A 9.6 A 9.9 B 10.2

100th Street SW and Lakeview Avenue SW B 13.1 B 16.5 B 16.9

108th Street SW and Lakeview Avenue SW B 11.1 B 12.7 B 13.0

Bridgeport Way SW and Pacific Hwy SW C 21.5 C 27.2 C 26.8

N. Thorne Lane SW and Union Street F 52.4 F 202.7 F 186.2

Berkeley Street SW and Union Street F 75.4 F 108.6 D 47.7

41st Division Drive at SB Ramps A 4.0 A 9.7 B 11.3

41st Division Drive at NB Ramps B 17.3 F 105.5 F 103.8

Barksdale Ave and NB I-5 Ramps D 53.1 F 168.5 E 69.6

Source: HDR Traffic Data Submittals

Notes: Delay is shown in seconds

Unsignalized intersections were not selected because they are not assumed to be "critical.”
September 2012 Point Defiance Bypass Project

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How were signalized intersections analyzed using the

WASIST model?

For the Project, WASIST (version 2.03) was used. The results from 

WASIST are based on USEPA approved MOBILE6 model (USEPA,

2003). The purpose of the model is to allow the user to conservatively 

estimate the highest CO concentrations that would be found at an 

intersection without having to perform a more time-consuming detailed 

analysis.

The WASIST program allows a two-phase approach to evaluating the CO 

concentrations of an intersection, the Pre-Screening Analysis and 

WASIST Screening Analysis. The pre-screening feature allows users to 

determine if a complete WASIST screening analysis is required by 

entering only a minimal amount of information. Passing results from the 

pre-screening analysis indicate that project effects do not violate the 

NAAQS for CO, and no further CO modeling is required. If a “fail” test 

result is indicated during the pre-screening analysis, a full WASIST 

screening analysis is required. The pre-screening and full WASIST 

screening analysis use a combination of worst-case conditions that, when 

occurring simultaneously, produce the highest levels of CO. 

The full WASIST screening analysis requires additional project-specific 

details in order to calculate project CO levels. The results of the WASIST 

analysis provide a pass or fail test result for the 1-hour and 8-hour worstcase CO concentrations. To verify compliance with the 8-hour CO 

NAAQS, the WASIST model adjusts by the USEPA-recommended 

persistence factor of 0.7 to conservatively estimate model-predicted 

8-hour average CO effects (USEPA, 1992). The WASIST model also 

factors in background concentrations to estimate maximum ambient 

1-hour average and 8-hour average CO concentrations, which are then 

compared against the CO NAAQS of 35 parts per million (ppm: 1-hour 

average) and 9 ppm (8-hour average). The 3.0 ppm background CO level 

used in this model is a WASIST model default value. 

WASIST modeling file printouts of input and output data and modeling 

results are presented in Attachment A. Traffic data used in the WASIST 

model was based on PM peak hour volumes, which was provided by the 

Project office. 

 3 A computerized screening model, used for estimating worst-case CO concentrations near 

signalized intersections and metered roadways.
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Chapter 3 – Affected Environment

What are the Puget Sound regional air quality trends?

Regional air pollutant trends have generally followed national patterns 

over the last 20 years. Although the average weekday VMT in the central 

Puget Sound region have increased from 30 million miles in 1981 to 65 

million in 1999 (PSRC, 2000), the pollutants associated with 

transportation sources have decreased. This is due to more stringent 

federal emission standards for new vehicles and the gradual replacement 

of older, more polluting vehicles.

Prior to 1996, the Puget Sound area was classified as a non-attainment 

area for CO because monitoring sites showed that CO concentrations had 

exceeded the NAAQS. The Puget Sound area encompasses a large portion 

of the Everett-Seattle-Tacoma urban area. In 1996, the area was

reclassified as a maintenance area for CO, meaning that the area has met 

NAAQS, and a maintenance plan would be implemented to prevent the 

area from being reclassified to non-attainment.

Another pollutant of interest in the Puget Sound region is particulate 

matter or dust, particularly the portion of dust that is less than 10 microns 

in size (PM10) or less than 2.5 microns (PM2.5). Particles of this size are 

small enough to enter the lungs when inhaled. The region is in attainment 

(meets NAAQS) for PM10, but since 2009 has been a designated as a 

nonattainment area for PM2.5. 

Over the past 20 years, air quality in the region has improved, even with a 

growth in both population and vehicle mile traveled (VMT). Much of the 

improvement in air quality is due to improvements made to emission 

controls on motor vehicles, the vehicle Inspection and Maintenance (I&M) 

program administered by Ecology, and the retirement of older, more 

polluting vehicles. However, over the past several years, levels of 

emissions of fine particulates have been on the rise, and new concerns 

such as air toxics and visibility have grown.

Emissions of nitrogen dioxide, sulfur oxides, and lead are below levels of 

concern in the region. Levels of sulfur dioxide (SO2) in the region have 

shown significant decreases in the last 20 years, and monitoring by the 

PSCAA ceased in 1999 for this pollutant. Lead in the ambient air is no 

longer considered a public health concern, and has not been monitored in 

the region since 1999. NOx are a concern in the region due to their role in 

the formation of O3 (along with VOCs in the presence of sunlight); 
September 2012 Point Defiance Bypass Project

Page 18 Air Quality Discipline Report

however, emissions of this pollutant have been dramatically reduced in the 

region.

The National Air Toxic Assessment is an ongoing comprehensive 

evaluation of air toxics in the United States conducted by the USEPA. The 

assessment indicates that air toxics risk in the Puget Sound region is 

similar to other major urban areas. The diesel exhaust contribution to the 

area’s toxic air pollutant concentrations should be reduced in the future as 

a result of federal regulations that require cleaner-burning diesel fuel for 

on-road vehicles and for off-road diesel engines. 

Voluntary programs, such as the local Diesel Solutions Program and 

Ecology’s Clean Cities Program, are in place to encourage public and 

private fleet operators to use ultra-low sulfur diesel and/or to install 

retrofit devices to filter or oxidize vehicle exhaust (PSCAA, 2005). 

Ecology and the USEPA support other voluntary programs that encourage 

diesel emission reductions.

What are the current air quality characteristics in the 

study area?

The project corridor traverses areas that are designated as maintenance 

areas for PM10 and CO; and as nonattainment for PM2.5.

In 1978, the central Puget Sound region was classified as a nonattainment 

area by the USEPA for CO. In 1987, the industrial areas of the Seattle

Duwamish River, Kent Valley and Tacoma Tideflats were classified as 

nonattainment areas for PM10. 

The Seattle and Tacoma industrial areas include the ports of both those 

cities. Areas designated as nonattainment have exceeded the NAAQS for 

those pollutants. In 1996, having met the federal standards for several 

years, the region was redesignated by the USEPA as a maintenance area 

for CO. The three PM10 areas have also met the federal standards for the 

past several years, and were redesignated as maintenance areas effective

May 14, 2001. 

A small part of Pierce County, the Tacoma tide flats, previously 

designated as a nonattainment area for PM10 is now a maintenance area for 

PM10. This PM10 maintenance area is within the project corridor.

Most of Pierce County was designated a nonattainment area for fine 

particle pollution (PM2.5) in 2009 because fine particle pollution levels too 

frequently exceeded the national limit. The study area is in attainment with 

the other NAAQS criteria pollutants – nitrogen dioxide (NO2), sulfur 

dioxide (SO2), and lead (Pb).
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For most pollutants, no air quality monitoring data are available for the 

immediate area to be affected by construction and operation of the project 

corridor. Depending on the pollutant, the nearest monitoring site is located 

anywhere from approximately one mile to 25 miles from the north end of 

the project corridor. Exhibit 2 below summarizes recent Puget Sound 

Clean Air Agency (PSCAA) ambient pollutant data from monitors closest 

to the project study area. 

Exhibit 4. Ambient Criteria Pollutant Concentrations near the Study Area

Year Location Pollutant Standard Pollutant 

Concentration

2010

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3

) 6.9 μg/m3

24-hour Average (μg/m3) 38 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 0.8 ppm

1-hour Average (ppm) 1.2 ppm

2009

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3) 9.8 μg/m3

24-hour Average (μg/m3) 46 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 1.0 ppm

1-hour Average (ppm) 1.4 ppm

2008

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3

) 9.8 μg/m3

24-hour Average (μg/m3) 44 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 1.0 ppm

1-hour Average (ppm) 1.6 ppm

2007

Port of Tacoma, 

2301 Alexander 

Ave, Tacoma WA

PM10

Annual Arithmetic Average (μg/m3) 17.7 μg/m3

24-hour Average (μg/m3) 54 μg/m3

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3) 9.7 μg/m3

24-hour Average (μg/m3) 43 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 1.0 ppm

1-hour Average (ppm) 1.4 ppm

2006

Port of Tacoma, 

2301 Alexander 

Ave, Tacoma WA

PM10

Annual Arithmetic Average (μg/m3

) 21 μg/m3

24-hour Average (μg/m3) 59 μg/m3

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3

) 9.5 μg/m3

24-hour Average (μg/m3) 37 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 1.5 ppm

1-hour Average (ppm) 2.3 ppm

2005

Port of Tacoma, 

2301 Alexander 

Ave, Tacoma WA

PM10

Annual Arithmetic Average (μg/m3) 23 μg/m3

24-hour Average (μg/m3) 64 μg/m3

7802 South L St, 

Tacoma WA PM2.5

Annual Arithmetic Average (μg/m3) 11.5 μg/m3

24-hour Average (μg/m3) 35 μg/m3

Beacon Hill, 

Seattle WA CO

8-hour Average (ppm) 1.9 ppm

1-hour Average (ppm) 2.7 ppm

Source: Puget Sound Clean Air Agency, Annual Air Quality Data Summary Reports, 2005 through 2010.
September 2012 Point Defiance Bypass Project

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What pollutants of concern exist in the study area?

Pollutants of concern in the study area are CO, PM10, and PM2.5 due to the 

historical and current exceedances of these criteria pollutants in the 

vicinity of the project. The sources of these pollutants, their effects on 

human health and the nation’s welfare, and their final deposition in the 

atmosphere vary considerably. A brief description of each pollutant is 

provided below. In addition to criteria pollutants, greenhouse gases and 

MSATs are also a concern and are described below. 

Carbon Monoxide

CO is a colorless gas that interferes with the transfer of oxygen to the 

brain. CO is emitted almost exclusively from the incomplete combustion 

of fossil fuels. Prolonged exposure to high levels of CO can cause 

headaches, drowsiness, loss of equilibrium, or heart disease. CO 

concentrations can vary greatly over relatively short distances. Relatively 

high concentrations of CO are typically found near congested 

intersections, along heavily used roadways carrying slow-moving traffic, 

and in areas where atmospheric dispersion is inhibited by urban “street 

canyon” conditions. Consequently, CO concentrations are predicted on a 

localized, or microscale basis. 

Because the Project is in a CO maintenance area, conformity rules require 

analysis of potential CO concentrations with applicable air quality plans.

Hot-spot modeling for CO emissions conducted showed that the Project is not 

predicted to cause or exacerbate a violation of the applicable NAAQS. No 

intersections would exceed the CO levels established in the NAAQS.

Particulate Matter 

PM pollution is composed of solid particles or liquid droplets that are 

small enough to remain suspended in the air. Of particular concern are 

those particles that are smaller than, or equal to, 10 microns (PM10) or 2.5 

microns (PM2.5). 

PM10 consists of very small liquid and solid particles floating in the air, 

which can include smoke, soot, dust, salts, acids, and metals. It also forms 

when gases emitted from motor vehicles or industrial sources undergo 

chemical reactions in the atmosphere. Major sources of PM10 include 

motor vehicles; wood-burning stoves and fireplaces; dust from 

construction, landfills, and agriculture; wildfires and brush/waste burning; 

industrial sources; windblown dust from open lands; and atmospheric 

chemical and photochemical reactions. Suspended particulates produce 

haze and reduce visibility. 
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PM10 poses a greater health risk than larger-sized particles. When inhaled, 

these tiny particles can penetrate the human respiratory system’s natural 

defenses and damage the respiratory tract. PM10 can increase the number 

and severity of asthma attacks, cause or aggravate bronchitis and other 

lung diseases, and reduce the body’s ability to fight infections. A review 

of available data indicates that all recently measured PM10 concentrations 

have been less than the levels allowed by federal, state, and local 

standards. (USEPA 2001)

Because the Project is in a PM10 maintenance area, conformity rules 

require analysis of potential project-related PM10 emissions.

PM2.5 results from fuel combustion (from motor vehicles, power 

generation, and industrial facilities), residential fireplaces, and wood 

stoves. In addition, PM2.5 can be formed in the atmosphere from gases 

such as sulfur dioxide, NOx, and VOCs. The main health effects of 

airborne PM2.5 are on the respiratory system. Like PM10, PM2.5 can 

penetrate the human respiratory system’s natural defenses and damage the 

respiratory tract when inhaled. Whereas particles 2.5 - 10 microns in 

diameter tend to collect in the upper portion of the respiratory system, 

particles 2.5 microns or less in diameter are so tiny that they can penetrate 

deeper into the lungs and damage lung tissues.

Because the Project is in a PM2.5 nonattainment area, conformity rules 

require analysis of potential project-related PM2.5 emissions.

Ozone

O3 is a colorless toxic gas that enters the blood stream and interferes with 

the transfer of oxygen, depriving sensitive tissues in the heart and brain of 

oxygen. O3 also damages plants by inhibiting their growth. Although O3 is 

not directly emitted, it forms in the atmosphere through a chemical 

reaction between reactive organic gases and nitrogen oxides, which are 

emitted from industrial sources and automobiles. Substantial O3

formations generally require a stable atmosphere with strong sunlight. 

In the proposed Project study area, the highest O3 concentrations occur 

from mid-May until mid-September, when urban emissions are trapped by 

temperature inversions followed by intense sunlight and high 

temperatures. Maximum O3 levels generally occur between noon and early 

evening at locations several miles downwind from the sources, after 

nitrogen oxides and hydrocarbons have time to mix and react under 

sunlight. For these reasons, the effects of the proposed Project on O3 levels 

are considered only on a regional basis. 
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Nitrogen Dioxide 

NO2 is a brownish gas that irritates the lungs. It can cause breathing 

difficulties at high concentrations. Like O3, NO2 is not directly emitted but 

is formed through a reaction between nitric oxide (NO) and atmospheric 

oxygen. NO and NO2 are collectively referred to as nitrogen oxides (NOx) 

and are precursors to O3 and PM2.5 formation. NO2 also contributes to the 

formation of PM10. At atmospheric concentrations, NO2 is only potentially 

irritating. In high concentrations, the result is a brownish-red cast to the 

atmosphere and reduced visibility. There is some indication of a 

relationship between NO2 and chronic pulmonary fibrosis. Some increase 

in bronchitis in children (2-3 years old) has also been observed at 

concentrations below 0.3 parts per million (ppm). 

Because the Project is not anticipated to substantially affect regional 

emissions of NO2, a regional NO2 analysis is not warranted; however,

annual operational NOx emissions were calculated because NOx is a 

PM2.5 precursor.

Lead 

Pb is a stable element that persists and accumulates in the environment 

and in animals. Its principal effects in humans are on the blood-forming, 

nervous, and renal systems. Pb levels in the urban environment from 

mobile sources, such as automobiles, have significantly decreased since 

the federally mandated switch to unleaded gasoline in 1995. 

Because the proposed Project is not anticipated to substantially affect 

regional emissions of Pb, a regional Pb analysis is not warranted. 

Sulfur Dioxide 

SO2 is a product of high-sulfur fuel combustion, and can be a precursor to 

PM2.5 formation. The main sources of SO2 are coal and oil used in power 

stations, industry, and domestic heating. Industrial chemical 

manufacturing is another source of SO2. SO2 is an irritant gas that attacks 

the throat and lungs. It can cause acute respiratory symptoms and 

diminished ventilator function in children. SO2 can also yellow plant 

leaves and corrode iron and steel. 

Because the Project is not anticipated to substantially affect regional 

emissions of SO2, a regional SO2 analysis is not warranted; however,

annual operational SO2 emissions were calculated because SO2 is a PM2.5 

precursor.
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Air Quality Discipline Report Page 23

Mobile Source Air Toxic (MSAT) Emissions

In addition to the criteria pollutants for which there are NAAQS, the 

USEPA also regulates air toxics. Toxic air pollutants are those pollutants 

known or suspected to cause cancer or other serious health effects. Most 

air toxics originate from human-made sources, including on-road mobile 

sources, non-road mobile sources (e.g., airplanes), area sources (e.g., dry 

cleaners), and stationary sources (e.g., factories or refineries). 

The CAA identified 188 air toxics, and 21 have been identified with 

mobile sources. In 2001, the USEPA identified six of the 21 mobile 

sources as priority MSATs. The six priority MSATs include:

• Benzene

• Formaldehyde

• Diesel particulate matter/diesel exhaust organic gases

• Naphthalene

• Acrolein

• 1,3-Butadiene

Benzene

Benzene (C6H6) is a volatile, colorless, highly flammable liquid that 

dissolves easily in water. It is found in emissions from burning coal and 

oil, motor vehicle exhaust, evaporation from gasoline service stations, and 

in industrial solvents. These sources contribute to elevated levels of C6H6 

in the ambient air, which the public may subsequently breathe in. If 

humans are subjected to acute (short-term) inhalation exposure to C6H6, 

the following may occur: drowsiness, dizziness, and headaches; eye, skin, 

and respiratory tract irritation; and unconsciousness at high levels of 

exposure. Chronic (long-term) inhalation exposure has caused various 

disorders in the blood. Reproductive effects have also been reported for 

women exposed by inhalation to high levels of C6H6.

Formaldehyde

Formaldehyde (CH2O) is a colorless gas with a pungent, suffocating odor 

at room temperature. It has been detected in ambient air, and the average 

concentrations reported in US urban areas range from 11 - 20 parts per 

billion (ppb). The major sources appear to be power plants, manufacturing 

facilities, incinerators, and automobile exhaust emissions. If humans are 

subjected to acute (short-term) and chronic (long-term) inhalation 

exposure, the following can result: respiratory symptoms; and eye, nose, 

and throat irritation. Limited studies involving human subjects have 

associated CH2O exposure with lung and nasopharyngeal cancer.
September 2012 Point Defiance Bypass Project

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Diesel Particular Matter/Diesel Exhaust Organic Gases

Diesel Particular Matter/Diesel Exhaust Organic Gases (DPM/DEOG) are 

a complex mixture of thousands of gases and fine particles emitted by a 

diesel-fueled internal combustion engine. One of the main characteristics 

of diesel exhaust is the release of particles at a relatively rate that is about 

20 times greater than from gasoline-fueled vehicles (on an equivalent fuel 

energy basis). Almost 94% of these particles have a mass that is less than 

2.5 microns in diameter. These particles are primarily composed of 

aggregates of spherical carbon particles coated with organic and inorganic 

substances that are mutagenic, cytotoxic, or carcinogenic.

Naphthalene

Naphthalene (C10H8) is a slightly water-soluble, two-ring aromatic 

hydrocarbon and is the most volatile member of the polycyclic aromatic 

hydrocarbons (PAHs). C10H8 is used in moth repellents, lavatory scent 

discs, and soil fumigants. It is also found in light petroleum fractions and 

in residues from refineries. Acute (short-term) exposure to C10H8 can 

induce the production of meth hemoglobin in the blood which does not 

bind oxygen and destruction of red blood cells in humans. Symptoms of 

chronic (long-term) exposure by C10H8 are less known possibly because 

humans are less efficient at C10H8 oxidation. 

Acrolein

Acrolein (C3H4O) is a water-white or yellow liquid that burns easily and 

is easily volatilized. C3H4O can be formed from the breakdown of certain 

pollutants found in outdoor air, from burning tobacco, or from burning 

gasoline. It is extremely toxic to humans from inhalation and dermal 

exposure. Acute (short-term) inhalation exposure may result in upper 

respiratory tract irritation and congestion.

1,3-Butadiene

1,3-butadiene (C4H6) is a colorless gas with a mild gasoline-like odor. 

Motor vehicle exhaust is the most common source of C4H6. In humans, 

acute (short-term) exposure to C4H6 by inhalation results in irritation of 

the eyes, nasal passages, throat, and lungs. Epidemiological studies have 

reported a possible association between C4H6 exposure and cardiovascular 

diseases.

What are the health effects from MSATs?

Only limited tools and techniques are available for assessing projectspecific health effects from MSATs. These limitations relate to emissions, 

dispersion, exposure levels, and health effects.
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Air Quality Discipline Report Page 25

Emissions

USEPA tools available for estimating motor vehicle MSAT emissions are 

not sensitive to key variables that determine MSAT emissions for highway 

projects.

Dispersion

The tools available for predicting MSATs dispersion into the environment 

are limited. The current dispersion models were developed for the purpose 

of predicting episodic concentrations of CO, to determine compliance with 

the NAAQS. Dispersion models more accurately predict maximum 

concentrations, rather than exposure patterns.

Exposure Levels and Health Effects

Even if emissions levels and MSAT episodic concentrations could be 

accurately predicted, shortcomings in current techniques for exposure 

assessment and risk analysis prevent reaching meaningful conclusions on 

project-specific health effects. Exposure assessments are difficult to make, 

because it is difficult to accurately calculate annual MSAT concentrations 

and to determine durations that people are exposed to those concentrations 

at a specific location.

In addition, the USEPA has not established regulatory concentration 

targets for the six priority MSATs that are appropriate for use in the 

project development process. 

How do climate and weather affect air quality? 

Weather directly influences air quality. Important meteorological factors 

include wind, temperature, and sunlight intensity. Temperature inversions, 

which are associated with higher air pollution concentrations, occur when 

warmer air overlies cooler air. During temperature inversions in late fall 

and winter, particulates and CO from wood stoves and vehicle sources can 

be trapped close to the ground, which can lead to violations of the 

NAAQS. 

What are the existing meteorology conditions?

Ambient air quality is a function of many factors, including climate, 

topography, meteorological conditions, and the production of airborne 

pollutants by natural or artificial sources.

The study area is subject to the same meteorological conditions that affect 

the Puget Sound. This region has a marine climate, dominated by cool, 

moist winds coming off the ocean. Temperature inversions are common 
September 2012 Point Defiance Bypass Project

Page 26 Air Quality Discipline Report

throughout the Puget Sound area in the fall and winter. They are 

characterized by stagnant atmospheric conditions that tend to trap and 

concentrate pollutants. In most cases, pollutant-trapping inversions have 

an upper “lid” at an altitude between 1,000 and 3,000 feet and occur 

during the night and break up by early afternoon. The Project lies at less 

than 1,000 feet elevation and thus lies within the areas subject to 

inversions.

During the summer, winds typically tend to be light and variable. The 

average wind velocity is less than 10 miles per hour (mph). Persistent 

high-pressure cells often dominate summer weather, creating stagnant air 

conditions. This weather pattern sometimes contributes to the formation of 

photochemical smog. Due to its location north of the major urban centers 

of Seattle/Tacoma and the northerly winds during the summer months, the 

study area generally experiences fewer instances of stagnant air 

conditions. 

Although the Puget Sound lowland is the most densely populated and 

industrialized area in Washington, there is sufficient wind most of the year 

to disperse air pollutants released into the atmosphere. Air pollution is 

usually most noticeable in the late fall and winter, under conditions of 

clear skies, light wind, and a sharp temperature inversion, when 

particulates and CO from wood stoves and vehicle sources can be trapped 

close to the ground. If poor dispersion persists for more than 24 hours, the 

PSCAA can declare an “air pollution episode” or local “impaired air 

quality.”

Ecology issues a daily Air Quality Index (AQI) using forecast 

meteorology and real-time pollutant monitoring. Since adoption of the 

AQI in the Puget Sound region, there have been several instances of air 

quality advisories in the “moderate” and “unhealthy to sensitive 

populations” categories. 
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Air Quality Discipline Report Page 27

Chapter 4 – Potential Project Effects

What air pollutants would the Project generate? 

The major airborne pollutants of interest for transportation-related projects 

are CO, particulate matter (PM), O3, and NOx; these are commonly 

referred to as criteria pollutants. Federal and state standards regulate these 

pollutants, along with two other criteria pollutants: SO2, and lead. Lead

and SO2 are not pollutants of air quality concern for transportation-related 

projects and therefore are not addressed in this analysis. 

Mobile sources emit six pollutants that the USEPA classifies as MSATs: 

benzene, formaldehyde, diesel particulate matter/diesel exhaust organic 

gases, naphthalene, acrolein, and 1,3-butadiene. 

These six priority MSATs are known or suspected to cause cancer or other 

serious health effects. For example, benzene is a known carcinogen found 

in gasoline. MSATs can also cause other environmental effects, such as 

damage to plants and animals. 

What are the construction effects caused by the Project?

Construction activities typically associated with roadway projects can 

temporarily generate PM (mostly dust) and small amounts of other 

pollutants. These emissions are often associated with earthwork and 

demolition activities. If uncontrolled, PM would also be generated by 

construction trucks entering roadways, depositing dust and mud on paved 

streets.

Heavy trucks and construction equipment powered by gasoline and diesel 

engines would generate CO and NOx in exhaust emissions. The use of 

diesel construction equipment will result in a temporary increase in MSAT 

emissions in the project area. If construction traffic were to reduce the 

speed of other vehicles in the area, emissions from traffic would increase 

slightly while those vehicles are delayed. These emissions would be 

temporary and limited to the immediate area surrounding the construction 

site. In addition, temporary odors may be detected by people near asphalt 

paving operations. These odors would decrease with increased distance 

from the source.

Construction activities would include demolition of pavement and other 

structures, earthwork, new rail construction, and new paving. Equipment 

to be used for construction would include truck cranes, vibratory 
September 2012 Point Defiance Bypass Project

Page 28 Air Quality Discipline Report

oscillator, dump trucks, loaders, excavators, and typical paving equipment 

such as graders, asphalt pavers, and rollers. The air emissions from these 

types of construction projects would slightly be greater for the Build 

Alternative than the No Build Alternative.

PM10 emissions may be associated with project construction, particularly 

for earthwork or demolition activities. PM10 emissions can vary from day 

to day, depending on the level of activity, specific operations, and weather 

conditions. PM10 emissions depend on soil moisture, silt content of soil, 

wind speed, and amount and type of equipment operating. Larger dust 

particles settle near the source, while fine particles are dispersed over 

greater distances from the construction site.

PM10 from construction activities is noticeable if uncontrolled. Mud and 

particulates from trucks are also noticeable if construction trucks are 

routed through residential neighborhoods. Minimization measures would

be in place during construction to ensure compliance with PSCAA’s

regulations, which require the control of dust during construction and 

prevention of deposition of mud on paved streets. Burning would not be 

allowed in the study area, so there would be no contribution of PM from 

burning.

What are the operational effects caused by the Project?

As discussed earlier, the Project must be reviewed under General 

Conformity rules (40 CFR 93, Subpart B) to ensure that the proposed

federal actions to fund and approve the Project are in conformance with 

SIPs. This type of conformity determination is required only for those 

pollutants for which the area is classified as nonattainment or 

maintenance, or for pollutants which are precursors to the nonattainment 

or maintenance pollutants.

General Conformity

Air quality was evaluated for rail operations as well as project 

construction. The focus of the General Conformity analysis was on shortterm construction effects as well as rail operational effects.

Project Construction Emissions

The Project would involve construction of approximately 3.5 miles of new 

track and upgrading of approximately 14.5 miles of track within the 

existing rail corridor. This construction is of similar size to a project 

analyzed in 2001 by the Surface Transportation Board (STB), for

construction of 3.2 miles of new rail line in Louisiana (STB 2001). The

pollutant of greatest concern for that project was nitrogen oxides (NOx) 

due to construction equipment exhaust emissions. Total NOx emissions 
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Air Quality Discipline Report Page 29

from that construction project were estimated by STB at 7.81 tons/year, 

using 1985 emission factors. Total annual emissions of other criteria 

pollutants were estimated at levels that were less than the estimated NOx

emissions for that project.

In comparison, the Project construction would have only slightly more 

new line construction, and upgrading of some existing rail line as 

described above. Even if the construction equipment activity were double 

that of the Louisiana project, and if old (pre-1985) construction equipment 

was used for the Project, total construction emissions for each individual 

criteria pollutant would be less than 16 tons/year. Also, because 

construction equipment engines have become cleaner in recent years with 

the advent and inclusion of better emission reduction technology, pollutant 

emissions from the existing construction equipment fleet are likely to be 

lower than assumed in the Louisiana study. 

Therefore, based on experience with other similar projects, the conclusion 

of this qualitative analysis is that the construction-related emissions from 

the Project would be far below the 100 tons/year General Conformity 

thresholds for NOx, VOCs, PM10, SO2, and CO (40 CFR 93, Subpart B). 

Project Operational Emissions

During operation of the Project, increased Amtrak service would result in 

a small decrease in the emissions of pollutants in the study area, and 

would change the location of operational emissions from the current 

coastal track alignment to the proposed in-land Point Defiance Bypass 

track alignment. The decrease in overall operational emissions comes 

despite the addition of daily Amtrak Cascade and Starlight trips due to the 

more direct route within the study area (and therefore fewer train miles 

traveled and fuel used overall on this section of track). Exhibit 4 presents 

estimated annual operational emissions for the Build and No Build 

Alternative.

Exhibit 5. Estimated Operational Emissions

Pollutant

Annual No Build 

Alternative 

Emissions 

(Tons)

Annual Build 

Alternative 

Emissions 

(Tons)

Annual Emissions 

Reduction under 

Build Alt (Tons)

CO 7.58 7.46 0.12

PM10 1.90 1.86 0.04

PM2.5 1.84 1.81 0.03

NOx 50.94 50.12 0.82

SO2 4.81 4.73 0.08

VOC 2.99 2.95 0.04
September 2012 Point Defiance Bypass Project

Page 30 Air Quality Discipline Report

The estimated operational emissions would be unlikely to affect overall 

ambient air quality in the study area. Diesel particulate matter would be 

small in relation to other nearby diesel sources, particularly the diesel 

truck traffic on local roads and highways. Also, Amtrak would use trains 

that have substantially lower emissions than USEPA standards for all 

pollutants in order to minimize health effects from diesel emissions such 

as CO, NOx, hydrocarbons, and PM. 

Conformity Statement

This discipline report provides an evaluation of potential air quality

emissions from construction and operation of the project. The project 

corridor crosses areas that are designated as maintenance areas with 

respect to the NAAQS for CO and PM10; and as a nonattainment area for 

PM2.5. As a federally-funded or federally-approved action, the Project

must be determined to conform to CAA requirements, in that the Project

must not interfere with approved state implementation plans to attain or 

maintain compliance with NAAQS in the area. 

Conservatively assuming that construction-related emissions of any 

criteria pollutant would be below 16 tons per year based on experience 

with similar projects, combined with the operational emissions annual 

estimates presented in Exhibit 4, the analysis shows that project-related 

emissions of pollutants of concern to the maintenance and nonattainment 

areas crossed by the project would be below the de minimis levels listed in 

General Conformity rules. Therefore, a General Conformity determination 

is not required for the Project, and implementation of the Project would be 

in conformance with CAA requirements. In other words, the Project is not 

expected to:

• Cause or contribute to any new violations of the NAAQS;

• Increase the frequency or severity of any existing violation of the 

NAAQS; or

• Delay the timely attainment of the NAAQS.

Local Carbon Monoxide Concentrations in the Study Area

The Project is not anticipated to create any new violations, nor increase 

the frequency of an existing violation of the CO standard at projectaffected, signalized roadway intersections; it would conform with the 

purpose of the current SIP and the requirements of the federal CAA and 

the Washington CAA.

Air quality hot-spot modeling for all selected intersections was performed 

for the existing year (2010) and for all the alternatives of the year of 

opening (2017) and the horizon year (2030), including the No Build 
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Air Quality Discipline Report Page 31

Alternative, and were modeled using the WASIST model. A full hot spot 

analysis was completed for all selected intersections. 

The following intersections were analyzed for CO effects:

• East “D” Street and East 26th Street 

• Barksdale Avenue and NB I-5 Ramps

• Berkeley Street and Union Avenue

The results for the worst-case receptor are below the 1-hour average 

NAAQS for CO of 35 ppm and below the 8-hour average standard of 

9 ppm. Te results show that the project would not be expected to cause 

exceedances of CO NAAQS at project-affected, signalized intersections 

under either the Build or No Build condition in any of the analysis years. 

Exhibit 6 provides the maximum CO concentrations of WASIST Model 

Outputs.

Exhibit 6. Maximum Predicted CO Concentrations 

Alternatives Intersections

Averaging Time

East “D” Street and

East 26th Street

Barksdale Avenue

and NB I-5 Ramp

Berkeley Street and

Union Avenue

1 hr 8 hr 1 hr 8 hr 1 hr 8 hr

2010 (Existing) 4.5 4.0 4.8 4.3 4.4 4.0

2017 No Build 4.1 3.8 4.3 3.9 4.0 3.7

2017 Build 4.1 3.8 4.3 3.9 4.0 3.7

2030 No Build 5.1 4.5 4.6 4.1 4.3 3.9

2030 Build 5.1 4.5 4.6 4.1 4.3 3.9

Notes: Concentration values are in parts per million. The one-hour NAAQS for CO is 35 ppm and for the 

eight-hour CO is 9 ppm. A background ambient CO concentration of 3 ppm was used in the WASIST 

modeling.

Mobile Source Air Toxic Emissions Level in the Study Area

The MSAT evaluation for the Project was prepared according to the 

FHWA 2009 Interim Guidance on Air Toxic Analysis in NEPA Documents

as a project with low potential MSAT effects. Based on the FHWA’s 

recommended approach for determining MSAT effects, the Project falls 

within this Tier 2-approach.

MSAT emissions are discussed qualitatively for the Project because 

operations are not expected to change among alternatives. The types of 

projects included in this category improve operations of highway, transit, 

or freight without adding substantial new capacity or creating a facility 

that is likely to meaningfully increase MSAT emissions.

For each alternative in the Project, the amount of MSATs emitted would 

be proportional to the vehicle miles traveled (VMT), assuming that other 
September 2012 Point Defiance Bypass Project

Page 32 Air Quality Discipline Report

variables such as fleet mix are the same for each alternative. Also, 

regardless of the alternative chosen, MSAT emissions would be lower 

than present levels in the design year as a result of the USEPA’s national 

control programs that are projected to reduce annual MSAT emissions by 

72 percent between 1999 and 2050.

Local conditions may differ from these national projections in terms of 

fleet mix and turnover, VMT growth rates, and local control measures; 

however, the magnitude of the USEPA-projected reductions is so great 

(even after accounting for VMT growth) that MSAT emissions in the 

study area are likely to be lower in the future in nearly all cases.

What are the indirect and cumulative effects of the Project?

Indirect

The Project is located within an existing rail corridor and urbanized area. 

The only potential indirect effect tied to the Project is that it may 

indirectly influence limited redevelopment near the relocated Amtrak 

Station at Freighthouse Square (see Land Use Discipline Report4). The 

PSCAA’s 2007 Growth Management Policies provide guidance for “air 

and climate friendly development” and redevelopment in the Freighthouse 

Square would be consistent with those policies (PSCAA 2007). 

Minimization measures would be in place during construction to ensure 

compliance with PSCAA’s regulations, which require the control of dust 

during construction and prevention of deposition of mud on paved streets. 

Thus, no indirect effect to air quality is expected.

Cumulative

In considering the cumulative effects of the Project on air quality, the 

Project’s direct and indirect air quality effects are evaluated in the context 

of the existing air quality conditions in the project area (which represent 

the past and ongoing activities that affect air quality) and the reasonably 

foreseeable future actions that would also affect air quality. As noted in 

Chapter 4, the study area is in a region that has experienced improved air 

quality over the past 20 years as a result of improvements made to 

emission controls on motor vehicles, the vehicle Inspection and 

Maintenance (I&M) program administered by Ecology, and the retirement 

of older, more polluting vehicles. Part of the PSCAA’s mission is “to 

improve neighborhood air quality and reduce greenhouse gases” through 

enforcing air quality regulations, conducting educational activities, and 

providing incentive programs to businesses and individuals to reduce 

emissions. While the region continues to grow and bring more traffic and 

other sources of emissions, improved access to transit, continued 

 4 WSDOT 2012
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 33

retirement of older vehicles, and technological advances to reduce 

industrial and household emissions will help to further improve regional 

air quality. The Project would not contribute to an adverse cumulative 

impact on air quality because it results in fewer emissions than current 

operations and is consistent with PSCAA’s policies for improving air 

quality in the region. 
September 2012 Point Defiance Bypass Project

Page 34 Air Quality Discipline Report

Chapter 5 – Recommended 

Minimization Measures

The Build Alternative would reduce operational rail emissions in the study 

area as a result of fewer overall train miles traveled. The Project would 

have short-term increases in construction-related emissions, but is not 

anticipated to have a significant effect of regional air quality. The 

estimated annual combined construction and operational air pollutant 

emissions are calculated to be below the de minimis levels under the 

General Conformity rules.

The Project will include some changes and upgrades to highway crossing 

intersections in the vicinity of the rail corridor, but would not result in CO 

NAAQS exceedances at bust intersections in the study area. 

The results of this air quality study indicate that no exceedance of the 

NAAQS will occur as a result of Project implementation. 

What minimization measure will be taken during Project 

construction?

Construction effects will be reduced by incorporating minimization

measures into the construction specifications for the Project. Possible 

minimization measures that may be implemented during construction to 

ensure compliance with NAAQS standards and PSCAA’s regulations to 

control PM10, deposition of PM, and emissions of CO and NOx during 

construction are listed below. 

If uncontrolled, fugitive dust from construction activities would be 

noticeable near construction sites. During construction, minimization

measures that comply with PSCAA regulations will be implemented. 

These regulations require the control of dust and mud deposits on paved 

streets during construction. 

In addition to particulate emissions, heavy trucks and construction 

equipment powered by gasoline and diesel engines generate CO and NOx

in exhaust emissions. If construction traffic reduces the speed of other 

vehicles in the area, emissions from traffic would increase slightly while 

those vehicles are delayed. These emissions would be temporary and 

limited to the immediate area surrounding the construction site. 
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 35

Construction emissions would contribute a small amount to total 

emissions in the study area, because construction traffic would be a very 

small fraction of the area’s total traffic. 

Some construction phases would result in short-term odors, particularly if 

asphalt is used for paving operations. Odors might be detectable to some 

people near the construction site. These odors would decrease as distance 

from the site increases.

Construction effects will be reduced by incorporating the minimization

measures outlined in the Associated General Contractor of Washington 

(AGCW) Guidelines into the Project’s construction specifications 

(AGCW, 1997). Possible minimization measures to control emissions of 

PM, CO, and NOx during construction include the following:

• Include specifications to comply with federal and state air quality 

regulations to cover temporary construction conditions such as dust 

and smoke emissions in the construction contract.

• To minimize fugitive dust emissions created during Project-related 

construction activities, the contractor will implement appropriate 

fugitive dust suppression controls, such as spraying water or other 

established measures, and operating water trucks on haul roads 

where possible to reduce dust.

• Spraying exposed soil with water to reduce PM10 emissions from 

soil disturbance and wind erosion.

• Covering and/or wetting materials transported by trucks, or 

providing adequate freeboard (space from the top of the material to 

the top of the truck) to reduce PM10 emissions during 

transportation.

• Providing wheel washers to remove PM that vehicles would

otherwise carry offsite to decrease PM on area roadways.

• Removing PM deposited on paved roadways to reduce mud and

windblown dust on area roadways.

• To limit Project-related construction emissions, FRA and WSDOT 

will work with the contractor(s) to ensure that construction 

equipment is properly maintained and that required pollutioncontrol devices are in working condition.

• Using appropriate emission-control devices on all construction 

equipment powered by gasoline or diesel fuel, to PM10, CO, and 

NOx emissions in vehicular exhaust.

• Using well-maintained equipment to reduce CO and NOx

emissions as it normally would if the equipment were operating 

within its first five years of operation.

• Covering dirt, gravel, and debris piles as needed with appropriate 

BMPs within the timeframes specified in the WSDOT Standard 

Specifications Manual to protect soil from wind erosion.
September 2012 Point Defiance Bypass Project

Page 36 Air Quality Discipline Report

• Routing and scheduling construction trucks in a manner that will 

reduce delays and the indirect air quality effects associated with 

traffic slowing to accommodate construction vehicles.

Based on these findings, no significant air quality effects would be 

expected with or without the Project, and no operational air quality 

minimization measures are necessary or proposed. However, BMPs for 

construction-related emissions could be implemented to reduce potential

temporary air quality effects during construction of the Project.

What minimization measures will be taken during Project 

operation?

Minimization measures would not be required for the Project since air 

quality impacts are not predicted to occur as a result of the implementation 

of the Build Alternative.
Point Defiance Bypass Project September 2012

Air Quality Discipline Report Page 37

References

Larson, Tim, et al. Local Background Values of Carbon Monoxide in Urban 

Areas. University of Washington and Washington Department of 

Transportation, 1993.

Surface Transportation Board, Environmental Assessment, Finance Docket No.

33877. Illinois Central Railroad Company, Construction and Operation –

in East Baton Rouge Parish, Louisiana. Washington, DC, July 20, 2001.

Trafficware, Traffic Signal Coordination Software, Synchro Version 6 (Build 

614), 2005.

United States, Code of Federal Regulations. Title 40, Part 50. National Primary 

and Secondary Ambient Air Quality Standards. 

_____. Title 40, Part 93, Subpart A. Conformity to State or Federal 

Implementation Plans of Transportation Plans, Programs, and Projects 

Developed, Funded or Approved Under Title 23 U.S.C. or the Federal 

Transit Laws.

_____. Title 40, Part 93, Subpart B. Determining Conformity of General Federal

Actions to State or Federal Implementation Plans.

United States Environmental Protection Agency. Air Data: Access to Air 

Pollution Data. http://www.epa.gov/air/data/index.html

Washington, Washington Administrative Code. Title 173. Department of Ecology.

Washington State Department of Transportation, Washington State Intersection

Screening Tool (WASIST) User’s Manual. Version 1.0, October 2005.Use 

this 

_____. 2009. Pacific Northwest Rail Corridor Tier 1 Environmental Assessment. 

Available at: 

http://wadot.wa.gov/Freight/publications/PNWRCReports.htm

_____. 2012. Point Defiance Bypass Project Land Use Discipline Report.
September 2012 Point Defiance Bypass Project

Page 38 Air Quality Discipline Report

FHWA (Federal Highway Administration). 2009. Interim guidance on air toxic 

analysis in NEPA documents. September 30, 2009.

Puget Sound Clean Air Agency (PSCAA).

2010. Air Quality Data Summary 2010.

2009. Air Quality Data Summary 2009.

2008. Air Quality Data Summary 2008.

2007. Air Quality Data Summary 2007.

2006. Air Quality Data Summary 2006.

2005. Air Quality Data Summary 2005.

2007. General information. Seattle, Washington. Web Page: 

http://www.pscleanair.org. Assessed November 2007.

Puget Sound Regional Council (PSRC). 1995. Guidebook for Conformity - Air 

Quality Analysis Assistance for Nonattainment Areas. September 1995.

US Environmental Protection Agency (USEPA).1992. Guideline for Modeling 

Carbon Monoxide from Roadway Intersections. Office of Air Quality 

Planning and Standards. Technical Support Division. Research Triangle 

Park, North Carolina. EPA-454/R-92-005.

US Environmental Protection Agency (USEPA).1997. Technical Highlights 

Emission Factors for Locomotives, EPA420-F-97-051. December 1997.

2006. 40 CFR Part 50: National Ambient Air Quality Standards for Particulate 

Matter. EPA-HQOAR- 2001-0017; FRL-RIN 2060-AI44. Sept. 21, 2006.

The Washington Association of General Contractors of Washington (AGC). Not 

dated. Guide to Handling Fugitive Dust from Construction Projects. 

Available from PSCAA.
Point Defiance Bypass Project September 2012

Air Quality Discipline Report

Attachment A